Derivatives  of  2,4,6-Trinitrobenzaldehyde 


BY 


EMIL  HAROLD  BALZ 


A  DISSERTATION 

PRESENTED    TO   THE    FACULTY    OF  THE  GRADUATE  SCHOOL  OF  THE 

UNIVERSITY  OF  PITTSBURGH  IN  PARTIAL  FULFILMENT  OF  THE, 

REQUIREMENTS  FOR  CANDIDACY  FOR  THE  DEGREE 

OF  DOCTOR  OF  PHILOSOPHY 


PITTSBURGH,  PENNSYLVANIA 
1920   . 


Derivatives  of  2,4,6-Trinitrobenzaldehyde 


BY 
EMIL  HAROLD  BALZ 


A  DISSERTATION 


PRESENTED    TO    THE   FACULTY   OF  THE  GRADUATE  SCHOOL  OF  THE 

UNIVERSITY  OF  PITTSBURGH  IN  PARTIAL  FULFILMENT  OF  THE 

REQUIREMENTS  FOR  CANDIDACY  FOR  THE  DEGREE 

OF  DOCTOR  OF  PHILOSOPHY 


PITTSBURGH,  PENNSYLVANIA 
1920 


t> 
V  2  vs :  i  A,  / 

V  •     tf     »?*•»•  VI/       .     , 

^ 


KXCHANOE 


ACKNOWLEDGMENT. 

The  author  wishes  to  express  his  gratefulness  and  indebtedness  to  Dr. 
Alexander  Lowy  for  his  untiring  assistance  and  patient  direction  during 
this  investigation. 


563057 


DERIVATIVES    OF    2,4,6-TRINITRO-BENZALDEHYDE. 

The  investigation  of  the  derivatives  of  2,4,6-trinitro-benzaldehyde 
was  undertaken  for  several  reasons.  An  examination  of  the  literature 
revealed  that,  compared  with  the  number  of  known  derivatives  of  benz- 
aldehyde  and  of  mononitro-benzaldehydes,  very  few  derivatives  of  this 
aldehyde1  had  been  prepared.  Undoubtedly,  a  comparison  of  the 
behavior  of  2,4,6-trinitro-benzaldehyde  and  of  benzaldehyde  itself  would 
show  interesting  facts  regarding  steric  hindrance  and  the  general  effect 
of  negative  groups  on  the  prqperty  of  the  compound.  Consequently, 
one  of  the  purposes  of  this  research  was  to  fill  in  the  gaps  in  the  list  of 
derivatives  of  2,4,6-trinitro-benzaldehyde  reported  in  the  literature. 

Since  2,4,6-trinitro-benzaldehyde  and  its  derivatives  are  explosive, 
they  have  been  of  considerable  interest  during  the  recent  past.  Ben- 
zaldehyde has  been  one  of  our  important  dye  intermediates  and,  reasoning 
by  analogy,  it  seemed  possible  that  2,4,6-trinitro-benzaldehyde  might 
also  find  some  use  as  a  dye  intermediate,  provided  some  cheap  process 
for  its  production  could  be  developed.  This  seemed  feasible,  especially 
at  the  present  time,  sinee  trinitro-toluene  would  furnish  a  cheap  and 
plentiful  source  because  of  the  large  stocks  of  this  material  now  on  hand 
and  the  necessity  for  its  disposal. 

The  method  used  for  the  preparation  of  2,4,6-trinitro-benzaldehyde 
is  essentially  that  described  by  F.  Sachs  and  Kempf.2  They  stated 
that  the  conversion  of  the  methyl  group  to  the  aldehyde  group  may  be 
accomplished  by  a  condensation  of  the  methyl  derivative  with  a  nitroso- 
dialkyl-aniline  and  subsequent  hydrolysis  of  the  condensation  product. 
(I).  R  —  CH2  +  ON.C«H4N(R),  =  R  —  C  :  NC6H4N(R)2  +  H2O 

I  I 

H  H 

(II).     R  —  C  :  N.C«H4N(R)2  +  H2O  =  R  —  C  :  O  +  H2N.C6H<N(R)2 

I  I 

H  H 

They  found  that  the  above  reactions  proceeded  easily  in  the  prepara- 
tion of  2,4,6-trinitro-benzaldehyde.  They  described  the  following  method 
for  its  production. 

1  Ber.,  35,  1236  (1902);  36,  960  (1903);  39,  2759  (1906);  Monatsh.,  31,  192  (1910)5 
Ber.,  35,  2704  (1902). 

1  Sachs  and  Kempf,  ibid.,  35,  2704  (1902);  36,  960  (1903);  35,  1224  (1902). 


Seventy  g.  of  2,4,6-trinitro-toluene  and  50  g.  ^-nitroso-dimethyl-aniline  in  an 
acetone  solution  were  refluxed  for  one  hour  with  30  g.  of  anhydrous  sodium  carbonate. 
After  the  mixture  cooled,  the  condensation  product  which  precipitated  was  filtered, 
washed  with  several  portions  of  25%  acetic  acid  and  then  boiled  with  water.  The 
condensation  product  was  then  dissolved  in  cone,  hydrochloric  acid,  and  extracted 
in  a  separatory  funnel  with  benzene. 

This  method1  gave  very  poor  results.  The  yield  was  only  15%.  Our 
investigations  led  to  numerous  modifications  of  the  details  of  operations, 
wrhich  will  be  described  in  the  experimental  part  of  the  paper.  This 
new  method  gave  a  yield  amounting  to  60%  of  that  calculated. 

The  reactions  investigated  were  of  the  general  type  known  as  con- 
densations and  take  place  in  2  steps. 

1.  Aryl-CHO  +  H,NR  =  Aryl-C^-OH     . 

\NHR 

The  second  step  consists  in  the  loss  of  one  molecule  of  water  by  the 
addition  product, 


2.  Aryl-C(-|OH 
\N|H 


R 


=  Aryl-CH  :  NR  +  H2O. 


These  condensation  products  are  known  as  "Schiff's  bases."2  In 
some  cases  the  2  steps  take  place  almost  instantly  while  in  others  the 
intermediate  product  can  be  isolated.  If  a  medium,  such  as  a  dilute 
solution  of  alcohol  and  water  is  employed,  the  tendency  is  to  form  the 
addition  product.  On  the  other  hand,  in  absolute  alcohol,  or  in  glacial 
acetic  acid,  the  tendency  is  to  yield  the  condensation  product  directly. 
Condensations  were  carried  out  between  2,4,6-trinitro-benzaldehyde  and 
the  following  substituted  amines:  aniline,  o-toluidine,  /3-naphthyl  amine, 
a-naphthyl  amine,  £>-toluidine,  1,3,4-xylidine,  diphenylamine,  ^-amino- 
azobenzene,  ^-aminophenol,  o-aminobenzoic  acid,  w-toluidine.  In  cer- 
tain cases  when  the  intermediate  product  is  isolated  and  dried  it  undergoes 
change  in  either  direction,  i.  e.,  it  either  decomposes  to  form  the  original 
aldehyde  and  the  amine,  or  it  loses  water  to  give  the  condensation  product. 
The  same  type  of  reaction  is  possible  with  substituted  aldehydes,  or 
amines,  or  witn  both. 

Steric  hindrance  also  seems  to  exert  considerable  influence  on  the 
condensations.  Spaeth3  could  not  condense  the  nitro-anilines  with 
2,4,6-trinitro-benzaldehyde.  Attempts  to  condense  them  are  under 
way.  The  nitro-anilines  have  been  condensed  with  other  nitro-benzalde- 
hydes  without  great  difficulty.  It  is  interesting  to  note  that  sulfanilic 
acid  fails  to  condense,  while  its  sodium  salt  offers  no  difficulty.  However, 
internal  neutralization  of  the  sulfanilic  acid  may  account  for  this  variation. 

1  Monatsh.,  31,  192  (1910). 

2  Ber.,  35,  984  (1902). 

3  Spaeth,  Monatsh.,  31,  192  (1910) 


Theoretically,  2  stereo-isomers  are  possible  with  carbon  and  nitrogen 
linked  as  they  are  in  the  case  of  these  condensation  products.  For  the 
anil,  the  following  forms  would  be  possible. 


V 

NO2  Syn-  NO2  Anti- 

Furthermore,  there  should  be  2  optically  active  isomers  in  the  case 
of  the  addition  products,  since  an  asymetric  carbon  atom  is  present. 

OH 
I 

p* -NT  TT 

V^-  ±\  XI 


NO2 

Further  experimental  work  on  the  identification  of  these  optical  isomers 
and  the  preparation  of  stereo-isomers  of  the  double  bond  carbon-nitrogen 
type  is  being  conducted  in  these  laboratories.  One  molecule  of  2,4,6- 
trinitro-benzaldehyde  may  be  made  to  condense  with  2  molecules  of 
tertiary  alkylated  aromatic  amines,  substituted  aromatic  amines,  or 
phenolic  bodies  to  produce  derivatives  of  triphenyl  methane.  Danck- 
wortt1  condensed  ^-nitro-benzaldehyde  with  phenolic  bodies.  Since 
these  condensations  present  possibilities  for  the  preparation  of  dye  stuffs, 
they  are  now  being  investigated. 

Experimental  Part. 

Preparation  of  2,4,6-Trinitro-benzaldehyde. — The  method  used  in 
the  preparation  of  this  compound  was  essentially  that  described  by 
Sachs  and  Kempf  and  Everding.2  When  the  details  of  their  method 
were  followed,  very  poor  yields  were  obtained.  Their  method  was  modi- 
fied so  that  finally  60%  of  the  theoretical  yield  was  obtained. 

A  solution  of  70  g.  of  trinitro-toluene  in  500  cc.  of  a  mixture  of  equal  parts  of  alcohol 
and  acetone  was  warmed  slightly  to  facilitate  solution  and  placed  in  a  jar  equipped  with 
an  agitator.  This  solution  was  treated  with  30  g.  of  anhydrous  sodium  carbonate  and 
50  g.  of  p-nitroso-dimethyl-aniline  added  gradually.  The  temperature  was  kept  below 
50°,  while  the  mixture  was  stirred  thoroughly  and  continuously.  The  addition  of  p- 
nitroso-dimethyl-aniline  required  an  hour  and  after  it  had  been  stirred  for  arfother  hour 
the  mixture  was  allowed  to  stand  for  at  least  24  hours.  It  was  then  a  solid  cake  of  the 
condensation  product.  By  means  of  a  large  Biichner  funnel,  as  much  of  the  mother 

1  Danckwortt,  Ber.,  42,  4163  (1909). 

2  Sachs  and  Kempf,  ibid.,  35,  1236  (1902);  Everding,  36,  960  (1903). 


8 

liquor  as  possible  was  removed.  The  solid,  placed  in  a  jar,  was  macerated,  thoroughly 
with  95%  alcohol  and  the  solution  was  filtered.  This  was  repeated  3  times  with  the 
solid.  Then  it  was  washed  with  25%  acetic  acid  solution  until  all  the  sodium  carbonate 
was  removed.  After  the  residual  solid  had  been  separated  and  dried,  it  was  powdered 
until  it  was  fine  and  gradually  added  to  a  jar  containing  150  cc.  of  cone,  hydrochloric 
acid.  When  the  mixture  was  stirred  thoroughly,  the  condensation  product,  nearly 
black  in  color,  changed  to  a  yellow  substance  almost  immediately. 

When  the  mixture  had  acquired  a  uniform  yellow  color,  it  was  transferred  to  a 
large  Erlenmeyer  flask,  the  jar  was  rinsed  with  cone,  hydrochloric  acid  and  an  equal 
volume  of  benzene  was  added  to  the  mixture.  After  the  flask  had  been  shaken  and 
heated  in  a  pail  of  hot  water,  it  was  set  aside  for  5  minutes,  when  the  upper  layer  of  the 
warm  benzene  solution  was  decanted  through  a  filter  paper.  More  benzene  was  added 
to  the  residue  and  the  extraction  repeated  until  the  aldehyde  had  been  exhausted. 
At  times  considerable  difficulty  was  encountered  because  of  emulsification.  The  com- 
bined benzene  extract  was  then  distilled  until  about  250  cc.  remained;  this  was  filtered 
while  still  warm.  As  the  solution  cooled  the  aldehyde  separated  in  crystals  with  ben- 
zene of  crystallization  which  was  lost  as  the  solid  dried.  The  pulverized  aldehyde, 
purified  by  washing  it  with  ether,  was  recrystallized  from  benzene.  M.  p.  119°. 

The  Product  of  2,4,6-Trinitro-benzaldehyde  and  Aniline,  C6H2(NO2)3-CHO.C«H6 
NH2. — This  compound  was  prepared  by  dissolving  2.41  g.  of  2,4,6-trinitro-benzaldehyde 
in  30  GC.  of  boiling  alcohol  and  adding  to  it  4  cc.  of  water,  and  finally  0.93  g.  of 
aniline.  This  solution  was  shaken  and  cooled  in 'an  ice-bath.  The  product  which 
separated  as  red  plates,  was  filtered  rapidly  with  the  aid  of  suction  and  washed  with  alco- 
hol containing  8  cc.  of  water  in  30  cc.  of  alcohol.  After  the  product  had  been  dried  as 
completely  as  possible  by  application  of  suction,  it  was  pressed  between  filter  paper  and 
finally  placed  in  a  desiccator  over  calcium  chloride  for  a  short  time.  M.  p.  86°.  On 
exposure  to  air,  aniline  was  evolved,  the  product  crumbled  and  lost  its  red  color,  to  form 
trinitro-benzaldehyde.  Aniline  could  be  identified  if  some  of  the  addition  products 
was  placed  in  a  small  test-tube  and  heated  very  gently.  A  rod  moistened  with  cone, 
hydrochloric  acid  was  held  at  the  mouth  of  the  test-tube;  anil^e  hydrochloride  was 
formed.  The  residual  2,4,6-trinitro-benzaldehyde  was  identified  by  its  melting  point. 
When  the  product  was  treated  with  glacial  acetic  acid  a  yellow  compound  resulted 
which  was  identified  later  as  the  condensation  product.  The  property  of  decomposing 
into  aniline  and  the  aldehyde  formed  the  basis  of  the  analysis.  A  weighed  quantity 
of  the  material  was  placed  on  a  watch  glass,  allowed  to  stand  at  room  temperature  and 
the  loss  in  weight  determined. 

Subs.,  0.1909,  0.0573:  loss,  0.0531,  0.0156. 

Calc.  for  C6H2(NO2)3CHO.(C6H6NH2):  C6H6NH2,  27.84.     Found:  27.81,  27.22. 

In  the  preparation  of  the  addition  compounds  listed  below,  the  ratio 
of  one  mole  of  2,4,6-trinitro-benzaldehyde  to  one  mole  of  the  substituted 

Analysis. 

M.  P.  , ^ . 

Product.  °  C.  Color.  Solubility.  Calc.  %.  Found  % 

2,4,6-Trinitro-benzaldehyde-     106  alcohol,       C6H4.CH3NH2 

o-toluidine reddish  chloroform,     =  30.74          30.54;  30.70 

2,4,6-Trinitro-benzaldehyde-  reddish  alcohol,       H2O  =  4.68       4.60;  4.58 

/3-naphthylamine brown  chloroform,  N  =  14.58        14.75;  14.76 

2,4,6-Trinitro-benzaldehyde-     ...  reddish  alcohol,       H2O  =  4.68       4.67;  4.51 

a-naphthylamine ........  brown  chloroform, 

2,4,6-Trinitro-benzaldehyde-  alcohol, 

diphenylamine 102  reddish  acetic  acid,   N  =  13.65        13.75;  13.89 

chloroform 


amine  was  used.  These  products  were  prepared  by  the  same  general 
method  as  that  used  for  the  aniline  addition  product  described  above.  These 
products  were  converted  into  the  condensation  products  when  treated 
with  glacial  acetic  acid  or  when  heated,  driving  off  the  water.  The 
table  given  above  contains  the  essential  results  obtained. 

2,4,6-Trinitrobenzal-aniline,  C6H2(NO2)3CH  :  NC6H6. — This  substance 
was  made  by  dissolving  3  g.  of  2,4,6-trinitro-benzaldehyde  in  25  cc.  of  glacial 
acetic  ajcid  and  adding  to  it  1.16  g.  of  aniline.  The  solution  was  heated  for  5 
minutes  on  a  water-bath  and  cooled.  A  light  yellow  crystalline  product  separated. 
After  3  recrystallizations  from  glacial  acetic  acid,  it  melted  at  220°,  with  decomposi- 
tion. Yield,  almost  quantitative.  This  compound  was  almost  insoluble  in  alcohol 
and  in  chloroform,  but  slightly  soluble  in  hot  glacial  acetic  acid. 

Subs.,  0.2000,  0.2000:  34.8  cc.  N  (34°,  733  mm.);  33.6  cc.  N  (28°,  733  mm.). 

Calc.  for  C6H2(NO2)8CH  :  N.C6H6  :  N,  17.72.     Found:  17.83,  17.64. 

Subs.,  0.2000,  0.2000:  CO2,  0.3621,  0.3653. 

Calc.  for  C6H2(NO2)3CH  :  NC6H6:  C,  49.36.     Found:  49.27,  49.80. 

Subs.,  0.2000,  0.2000:  H2O,  0.0460,  0.0481. 

Calc.  for  C6H2(N02)3CH  :  NC6H6:  H,  2.55.     Found:  2.57,  2.64. 

In  the  preparation  of  the  condensation  products  listed  below  the  same 
general  method  was  used  as  described  above  for  the  preparation  of  the 
anil.  Glacial  acetic  acid  was  used  as  solvent  in  all  cases.  The  mixtures 
were  heated  on  a  water-bath  for  from  5  to  30  minutes  to  complete  the 
reactions.  The  yields  obtained  were  almost  quantitative. 

Analysis  for  N. 

M.  P. 
Product.  •  C. 

2,4,6-Trinitro-benzal-o- 

toluidine 177 

2,4,6-Trinitro-benzal-/3- 

naphthylamine 192 

2,4,6-Trinitro-benzal-a- 

naphthylamine 242 

2.4,6-Trinitro-benzal-£- 

toluidine 179 . 5  yellow 

2,4,6-Trinitro-benzal- 1 ,3,4- 

xylidine 203 

2,4,6-Trinitro-benzal-£- 

amino-azobenzene 189 

2,4,6-Trinitro-benzal-£- 

aminophenol 179 

2,4,6-Trinitro-benzal-<?- 

aminobenzoic  acid 146 

2,4,6-Trinitro-benzal-w- 

toluidine 173.5 

Summary. 

1.  The  anil  of  2,4,6-trinitro-benzaldehyde  (m.  p.  162°)   prepared  by 
Sachs  and  Everding1  from  an  alcoholic  solution  was  made  and  analyzed. 
1  Sachs  and  Everding,  Ber.,  35,  1236  (1902) ;  ibid.,  36,  960  (1903). 


Color. 

Crystallizing     Calculated, 
media.                    %. 

Found. 

%. 

acetic  a«id 

yellow 

chloroform 

16.99 

17.24; 

17.10 

yellow 

acetic  acid 

15.30 

15.35; 

15.30 

orange 

acetic  acid 

15.30 

15.17 

yellow 

alcohol 

16.99 

17.09; 

17.08 

yellow 

alcohol 

16.28 

16.24; 

16.44 

brick  red 

acetic  acid 

20.00 

19.95; 

20.07 

yellow 

alcohol 

17.11 

16.95; 

16.82 

brick  red 

acetic  acid 

15.50 

15.38; 

15.60 

yellow 

alcohol 

16.99 

17.05; 

16.85 

10 

Their  results  were  checked  satisfactorily.  A  different  compound,  however, 
was  obtained  when  glacial  acetic  acid  was  used  as  a  solvent.  Its  melting 
point  was  220°.  The  carbon,  hydrogen  and  nitrogen  determinations 
showed  it  to  be  an  anil.  These  2  compounds  are  probably  isomers  of  the 
syn-  and  anti-type.  Attempts  to  prepare  similar  isomers  of  the  toluidines 
were  unsuccessful.  The  same  compound  was  obtained  if  alcohol  instead 
of  glacial  acetic  acid  was  employed  in  the  reaction. 

2.  Fifteen    derivatives   of   2,4,6-trinitro-benzaldehyde   were   prepared, 
analyzed  and  certain  physical  properties  determined. 

3.  The  intermediate  addition  products  were  prepared  in  the  case  of 
aniline,    o-toluidine   and   of   the   naphthylamines.     The   aniline   and   o- 
toluidine    compounds   lose    aniline    and    o-toluidine    respectively,    while 
the  naphthylamine  products  lose  water  and  are  converted  into  the  con- 
densation products. 

4.  The  intermediate  products  are  all  reddish-brown  in  color  and  are 
very  soluble  in  alcohol,  while  the  condensation  products  have  yellow  to 
brick  red  colors,  are  not  easily  soluble  and  have  much  higher  melting  points. 

5.  These  compounds,  like  many  other  similar  condensation  products, 
9**e  affected  to  a  greater  or  less  extent  by  the  action  of  light. 


BIBLIOGRAPHY. 
1-  Ber.,  35,  984  (1902). 

2.  Ibid.,  35,  1236  (1902). 

3.  Ibid.,  35,  2000  (1902). 

4.  Ibid.,  36,  960  (1903). 

5.  Ibid.,  39,377  (1906). 

6.  Ibid.,  39,  2759  (1906). 

7.  /W<£,  40,  3230  (1907). 

8.  Ibid.,  41,  2296  (1908). 

9.  Ibid.,  45,  3055  (1912). 

10.  Monatsh.,  31,  192  (1910);  Centr.,  1910,  2-455. 


VITA. 

Emil  H.  Balz  was  born  May  28,  1892,  in  Columbus,  Ohio.  His  ele- 
mentary and  high  school  training  was  received  in  the  public  schools  of 
Columbus,  after  which  he  enrolled  at  Ohio  State  University  and  graduated 
with  the  degree  of  Bachelor  of  vScience  in  Chemical  Engineering  in  1914. 
After  remaining  at  Ohio  State  University  for  two  years  and  spending  one 
summer  at  the  University  of  Chicago,  he  entered  the  University  of  Pitts- 
burgh as  instructor  of  organic  chemistry  and  continued  to  fulfill  the  re- 
quirements for  the  degree  of  Doctor  of  Philosophy. 


t> 


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